This is my first post here, and this topic is naturally one that I looked into when I first began studying astrology back in 1978. I soon discoverd that both Tropical and Fagan/Bradley Sidereal positions were important, and in fact I also sometimes look at other reference points as well. I leave statistical studies to others, but my chart files and rectifications of historical charts were the keys that led to my use of both zodiacs. Robert Blaschke has posted one of the more powerful pieces of anecdotal evidence here regarding the conjunction of Obama's Tropical sun to McCain's Sidereal sun: viewtopic.php?f=22&t=7#p23
I have posted many messages over on Jim Eshelman's Solunars board, and if you're seriously interested in Western Sidereal I recommend that you browse through the topics there. Here is part of a post that I think qualifies as research, though a much larger sample and more comparisons would solidify the usefulness of this remarkable technique. If someone has seen many such contacts in the Tropical zodiac, it would suggest that both are important when using this technique. Originally posted here: http://solunars.net/viewtopic.php?f=28& ... nics#p1244
This is an excerpt from a little ebooklet I wrote, with other notes on why the 9th and 12th harmonics in the Fagan/Bradley Sidereal zodiac are powerful charts. Jim Eshelman added some powerful examples from his own files.
A Time to be Born
When I was born the Sun was at sidereal longitude 202:17:28. When my father was born the Moon's position was 22:13:15, so that my Sun is closely opposing his Moon. The positions of my older brother's and step-mother's Suns are close together, since they were born on the same calendar day, January 11. The first Sun position is at 267:09:44, and the second is at 266:22:01, less than 1 degree away.
These connections seem intriguing enough, but there are other powerful contacts that become apparent only with some rather esoteric geometry and mathematics. In India there are derivative charts calculated from the natal chart using a method that divides the 360° ecliptic circle into smaller subsets. For example, by dividing the circle into 9 smaller "zodiacs" and folding them on top of one another, each mini-zodiac will span 40°, and every point that is a multiple of 40 degrees apart will be in conjunction in the new subsidiary chart. The same will be true of other divisions, such as 12 or 16. In the West these derivative charts are called harmonic charts. To calculate such a chart you can multiply the longitude of the original point by the circle division, then use the new longitude in your harmonic chart, making sure that it is less than 360° by eliminating any excess from the product. Thus a point at 10° in the root or radix chart will be at 90° in the ninth harmonic chart (10x9) and at 120° in the twelfth harmonic chart.
By multiplying the sidereal longitude of my father's natal Moon by 12 it is found to have a harmonic position of about 266:39, only 17 arc minutes from his second wife's natal Sun. The twelfth harmonic position of his Moon is also about 31' from the Sun's position in his first child's horoscope--my older brother. My 12th harmonic Sun is at 267:29:39, about 20' from my brother's Sun, and just beyond the 1° orb that I allow with this technique for a conjunction to my step-mother's Sun. I chose to live with these three people when I was a teenager instead of with my mother and step-father.
Here was another powerful, personal confirmation that made it even more difficult for me to believe that astrology was mere fantasy. In later years I found many other confirmations of the power of this technique, which is actually not used by most astrologers.
It is also worth pointing out that the exact absolute longitude of the radix position has a critical bearing on the accuracy of the method. A difference of only 5' in the initial position becomes 45' in the 9th harmonic and 60'—a full degree--in the 12th. Since an orb, or zone of influence, of only one degree is allowed, the initial position must be based on a sidereal longitude that gives a best fit when comparing charts. Western Sidereal positions--discovered in the 1950's--work very well, while those used most extensively in India do not. Tropical positions also do not appear to be effective.
Here is more data from my old files, with all positions in the Fagan/Bradley Sidereal zodiac, conjunctions with orb of less than one degree:
An astrologer friend had natal Uranus at 26GE21, with a ninth-navamsha harmonic position at 27TA06, conjunct her natal Mercury at 27TA33.
My natal Moon at 25LE49 gives a 12th H of 9AQ45, conjunct the above friend's natal Moon at 9AQ06.
A girl I was quite fond of had natal Venus at 12CP09, 12th H 25LE52, conjunct my natal Moon at 25LE49.
Another female friend had natal Moon at 2GE51, 9th H 25LI40, conjunct my ASC at 25LI35.
Close female friend (and friend of the above girl) natal Venus 17LE08, 12th H 25LI32, also conjunct my natal ASC at 25LI35.
Niece (by marriage) natal Moon 22SA30, 9th H 22LI26 conjunct my natal Sun 22LI17.
Co-worker who became a cosmetologist, natal Moon at 7VI23, 9th H 6PI27, conjunct her natal Venus at 6PI59.
Numerologist friend had natal Mercury at 16LI22, 12th H 16LI24 conjunct her natal Mercury!
Choreographer and dancer had her natal Neptune at 18LI33, 9th H 16PI56 conjunct her natal Mercury at 16PI57!
Former sister-in-law, natal Moon at 12CP07, 12th H at 25LE21 conjunct my natal Moon.
Woman's natal Moon at 16CA33, 12th H 18LI31 conjunct her daughter's natal Sun at 18LI43.
Using 15 data the combined error totaled minus 121 arcseconds, with an average error of about minus 8", meaning that adding 8" to the commonly calculated Fagan/Bradley ayanamsha would give a best fit to this small sample. I consider this to be a neutral result, and do not think that changing the ayanamsha would be warranted without much further work. Donald Bradley came up with his value back in 1957 I believe by working with more than one hundred ingress charts, mostly Lunar and Solar sidereal Capricorn ingresses.
I would be very interested in what others find using this approach.